This invention is an improvement om my prior prefabricated roofing panel, titled "Roofing Systems", Ser. No. 649,309, filed Sept. 11, 1984. In that patent application, a prefabricated panel having an attached waterproof membrane is described. The membrane is adhered to the top surface of the panel leaving uncovered an edge strip along each side edge of the panel. The prefabricated panels are installed in rows with alternate rows of spacers, a further waterproof membrane being installed at the roofing site to cover each row of spacers and the adjoining uncovered edges of the roofing panels.
Gantner, U.S. Pat. No. 4,078,349, provides an insulated lining for a roof consisting of rectangular boards, each board being covered with a hard covering including a headlap and a sidelap. The system of Gantner is not a waterproof roofing system, but is a system of using insulation panels for interior use. Warner, U.S. Pat. No. 3,468,086 describes an interlocking prefabricated roofing system having a stepped interlocking system. The system of Warner does not allow for any irregularities in the roofing and the panels must fit into each other exactly. Johnson, U.S. Pat. No. 2,717,668, shows a panel having obliquely cut ends which are set adjacent to each other to provide a tight seal. The panel is described for interior use.